1. Field of the Invention
The present invention relates generally to electrical distribution equipment and, more particularly, to an electrical recloser apparatus including an electronic control assembly and an external operating assembly including an operating arm which serves as a manual opening and closing lever and also as a lockout indicator.
2. Discussion of the Prior Art
In a conventional recloser, an oil insulated interrupter is provided within a tank and an external operating mechanism is mounted to the tank so as to be accessible by a lineman.
In the known recloser constructions, the external operating mechanism includes an operating arm that is movable between upper and lower positions to manually initiate closing and opening of the contacts of the interrupter within the tank. Closing energy is typically supplied by a relatively large closing solenoid which simultaneously charges one or more opening springs in preparation for a tripping operation. During operation of the known devices, fault currents are sensed by a trip solenoid which initiates tripping of the contacts by releasing the opening springs. Thereafter, a hydraulic control mechanism carries out time-delay operations and regulates the number of operating cycles to lockout of the recloser. Examples of a single-phase recloser incorporating this construction are the Types D and DV hydraulically controlled, single-phase reclosers marketed by McGraw-Edison, while examples of a three-phase recloser of this construction are known from the Types RV, VW and WV reclosers marketed by McGraw-Edison.
Although the operating mechanism of conventional recloser devices is easy to use and has found acceptance in the field by linemen who are familiar with the operation thereof, several drawbacks have been found to exist in the use of such reclosers wherein a hydraulic control mechanism is used to carry out the timing and cycles-to-lockout regulating functions within the recloser. For example, because the fluid in the tank of a hydraulically controlled recloser is relied upon to serve as dielectric fluid, interruption fluid and timing fluid, the viscosity thereof is a factor in most of the operations carried out by the controller.
Because the viscosity of the fluid is effected by the temperature thereof, and this temperature changes significantly with the ambient temperature, the timing operations conducted by the controller may be adversely effected thus causing a delay to occur in the reclosing operation of the device such that other equipment within the distribution system that is coordinated with the specific preferred timing operations of the recloser fail to operate in the designed manner and failure of the system may result.
Further, it is difficult to program a hydraulically controlled recloser due to the requirement that hardware within the sealed interior space of the known reclosers must be replaced in order to vary timing characteristics and the like of the recloser. Typically, a consumer specifies the desired time-current characteristics and timing sequence and purchases a pre-set recloser having "fast curve" or "slow curve" attributes. Thus, in order to ensure that a desired recloser type will be in stock when needed, a utility may be compelled to purchase several reclosers with different pre-set characteristics in order to fill their need.
The use of an electronic control assembly in a recloser is known with respect to certain conventional three-phase reclosers. For example, the Types RVE, VWE and WVE three-phase reclosers marketed by McGraw-Edison employ an electronic control mechanism which functions in a manner similar to the hydraulic reclosers discussed above, but are provided with electronic control of the timing operations within the device.
In the known three-phase electronic recloser constructions, an external operating assembly is typically provided which includes an operating arm for initiating manual opening and lockout of the interrupter so that a lineman can interrupt current flow through the reclosers when carrying out maintenance on the distribution system. In addition, it is known to employ a separate indicator arm which is movable between two positions to indicate the condition of the contacts of the recloser.
Other known three-phase reclosers incorporating electronic control employ a switch box having a lever switch or the like for permitting manually actuated opening and closing of the interrupter contacts. In many of these devices, a separate indicator is provided which is movable between two positions to indicate the condition of the interrupter at any given time during operation of the recloser.